Position regulated gun mount



Jan., i946, c. R. HANNA ET AL 2,3%,955

POSITION REGULATED GUN MOUNT Filed Feb. 10, 1942 5 Sheets-Sheet l c. R. HANNA ET AL 2,391,955

POSITION REGULATED GUN MOUNT Filed Feb. lo, 1942 5 SheetS-Sheet 2 AJM, IN1 i y 2 w 7%7 Mw ma. N l 9 2 f4 W 3 3 W7 m, a 7 v s. a J. 1 y m x wlw v m J ,A m J no n I. W. W @C Jan., L i946,

jan. E, 1946, c. R. HANNA ET AL POSITION REGULATED GUN MOUNT Filed Feb. 10, 1942 3 Sheets-Sheet 5 iNVENTORS CMN-ron RHmewn am nv/Rance .Lwm

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ATTORNEY Patented Jan. l, 1946 POSITION REGULATED GUN MOUNT Clinton R. Hanna, Pittsburgh, and Lawrence B.

Lynn, Wllkinsburg, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh. Pa., a corporation of Pennsylvania Application February 10, 1942, Serial No. 430.200

` claims. (ci. ssl-41) Our invention relates to a position regulator, particularly one including a gyro stabilizer for maintaining an element in a predetermined but adj ustable position.

An object of our invention is to provide a means for remotely locating a gyro stabilizer from the element which it controls when necessitated by space limitations such as in an army tank.

A more specific object of our invention is to provide, in a gun mounting assembly in a tank or other similar frame structure, a parallelogram linkage means so connecting the gyro stabilizer and the gun .which it controls, that although remotely situated from the gun and pivoted on some fixed axis. the gyro stabilizer will be acted upon in direct ratio to movements of said gun.

Another specific object of our invention ls to provide in a gun mount, a manually operated elevating mechanism for the gun with a flexible driving means connecting the elevating means to the gyro stabilizer in such a fashion that the gyro stabilizer may be operated by the hand wheel of the elevating means and furthermore, by said flexible driving means, eliminate the necessity of disconnecting the gyro stabilizer from said elevating mechanism during manual adjustment oi' the gun.

Further objects and advantages will become more apparent from a study of the following specilcation when considered in conjunction with the accompanying drawings, in which:

Figure 1 is a perspective view of a gun control assembly embodying the principles of our invention and installed within a tank:

Fig. 2 is an enlarged view partly in section showing the parallelogram linkage and ilexible driving means included in Fig. 1;

Fig. 3 is an enlarged perspective view of the anticipating gyro of the gyro stabilizer assembly included in Fig. 1:

Fig. 4 is an enlarged vertical section of the bearing mounting of the anticipating gyro .taken along a plane dened by the :c and y axes as viewed from the left;

Fig. 5 is a schematic showing of the position regulating control system embodied in Fig. 1;

Fig. 6 is a graph of the velocity curve plotted against the displacement curve of the gyroscope;

Fig. 7 is a fragmentary elevation, with parts shown in section, as viewed from the breech end of the gun;

Fig. 8 is a detail View taken along line VIII- VIII oi Fig. 7;

Fig. 9 is a sectional view taken along line IX- IX of Fig. 2; and

Fig. 10 is an enlarged detail view of the gyrovertical shown in Fig. 1.

Referring to the drawings. we have, in Figures 1 and 2, a gun I mounted on a tank turret 3 together with a, stabilizer assembly indicated generally at 5 for correcting for angular disturbances such as. pitch or roll. Pitching is the rocking movement in a vertical plane in the direction of travel of the tank while rolling is movement about an axis in the direction of travel. 'Ihe gun is pivotally mounted on trunnions 1 in the forward wall of the turret 3 which trunnions constitute an axis in a horizontal plane and at right angles to the gun-barrel axis giving freedom of gun movement in the elevation plane only. Azimuth movements of the gun may be achieved by rotating the gun turret or by laterally steering the tank, for example. .A

The gyro stabilizer. while forming no part oi our invention per se, will be briefly described so that our invention may be more readily understood.

The gyro stabilizer assembly 5, described in more detail and claimed in a copending application of C. R. Hanna, Serial No. 366,877, filed November 23, 1940, entitled Gun stabilizers, includes as a componet part, a "gyro vertical" so called because its axis of spin continuously tends to seek the vertical; thereby constituting a basis or reference for positioning a gun with respect to a distant target. The invention in said patent application is especially adapted to control the movements of a gun which is pivotally mounted on a tank so the gun, once aimed at a distant target, will be continuously trained on such target irrespective of disturbances or disturbing movements of the tank in the course of its travel. The

numeral 9 denotes a support which must be. so

mounted as to partake of the pitching movements of the gun and yet be adjustably mounted with respect to the gun. -As elsewhere herein described, .the controlling elements of the stabilizer are sensitive to change in angular position of the supporting element 9 and provision is made for changing the angular relation of the supporting element and the gun to change the elevation of the latter. The controlling elements render the stabilizer effective to oppose change in angular position of the gun and therefore of the supporting element connected to move angularly therewith, with the result that the gun may be maintained aimed at the target within a narrow range of deviation. As a reference vertical is preferably employed in connection with the controlling elements, the latter assure of operation oi the sta- Thus, with the angular position oi the supporting element xed by the biasing means or vertical reference, it is assured that the stabilizer will not v only minimize deviation of the sun from aimed position but will restore the gun to that position with the supporting element in the position fixed by the reference vertical. Numeral ii designates ,l

a bracket which is rigidly mounted on support 3 and .which has pendulously mounted thereon in bearings a U-shaped pendulous -rnember I3 in such position that it may move angularly aboutv v the upper :c axis. It is apparent that if support i 3 were to be gradually tilted in its own plane,

pendulous member I3 would tend, at alltimes, to`

align itself with the center of the earth due to gravity. However, if such tilting movement were to become violent or if such support wereto have vibratory movement of medium or high frequency,

pendulous member I3 would become quite unstable and would tend to oscillate to such an extent that it could no longer be reliable as a means for indicating the direction of the earths center. In order to stabilize the movement oi pendulous member I3 a gyro vertical i5 is provided which is mounted in gimbals in bracket!! in a position that it may pivot about the z and a' axes. 'A motor denoted generally by M is located within the housing i1 and drives a flywheel i8 whichconstitutes a gyro wheel. Since such gyro wheel has a vertical axis of spin and since the motor and gyro assembly are pendulously mounted in gimbais, the gyro wheel axis will inherently and gradually seek a vertical or earth's center alignment position. If there were no friction in the universal gimbal mount and no other restraining force the gyro wheel axis would oscillate in a corical path indefinitely once its axis was tilted from the vertical. Friction at the gimbal bearings or any other resistance to such conical motion tends to precess the gyro wheel axis back to vertical in s .spiral path. Constant friction, however, is highlyl undesirable because it prevents a complete rturn Ioi* the gyro wheel to its earth's center pointing position. A frictional damping means inthe form of a ilat strip or track member 2| having friction forming sides isrigidly fastened ito thebottom of pendulous member i3. It is so *positioned that it may be frictioraily engaged by friction shoes projecting inwardly from the uV Vbracket 23 supported on U piece 25 rigidly fastened to block 21 which clamps the gyro wheel in position and which carries it pivotally on bearings in its gimb'als. 'Ihe friction damper `iust described represents an improvement over that used in said copending application. In said copending application a channel was used in place of the at strip 2|. It was mounted in the same position in a manner that friction shoes mounted 'on a rod in place of bracket member 23 were positioned within the channel (instead of exterior thereof as i shown in the present device) and i'rictionally engaged'by its sides. Such channel member however had a tendency 'to warp, destroying the accuracy of the spacing of the sides of the channel and binding the friction shoes in the course of their travel within the channel. While warping may not be absent from the at strip member it is obvious that such distortion will not increase the thickness of said strip. Consequently while the friction shoes might not travel along a perfectly straight track there will be no binding to restrict their travel. Y

Forces which would normally rotate or displace pendulous'member. I3 about its a: axis are transmitted to the gyro vertical by the mechanical connection described above, attempting to displace it about its a: axis. This displacement force instantly causes the gyro to process at right angles to the applied force about its z axis. The

precessional movement of the gyro through the above mechanical connection with pendulous member I3 exerts a reaction force opposite to the force of displacement, thereby, within the capacities of the gyro, substantially maintaining the pendulous member I in a vertical or earths center pointing position. Precessional velocities of the gyro about its z axis-move the friction shoes with respect to track 2 I. Sliding friction forces so developed are proportional to the'precessional velocity. Displacement oi the pendulous member I3 from the vertical is opposed by the gyro I5, torque applied by the pendulous member to the gyro causing the latter to precess about the precession or e axis and precessional velocity being accompanied by a gyroscopic or reaction torque which opposes the applied torque. As the gyroscopic or reaction torque is applied as a force normalto the friction surfaces of the track 2| and the shoes, friction force is developed and is effective as a couple about the precession axis to damp precessional oscillations in proportion te precessional velocity. As the precessional velocity approaches zero in response to displacement velocity approaching zero the sliding friction forces approach zero, consequently there is no error arising from this type of damping. The damping will be in wholly one plane as defined by the axes 1l and :c and the gyro wheel axis will spiral inwardly in an 'unsymmetricai manner, that is somewhat of the form of a very flat elliptical spiral, with its larger axis located along the track 2|. This dissymmetry is caused in part by the pendulousness of member i3 about the-a: axis. Since only one axis of accuracy is required, namely the :c axis, the smaller stability about the s axis has no eiect on the performance of the device. Sudden stopping or starting of the tank when the gun i5 pointed in a plane substantially parallel to the direction of travel will slightly displace thependulous member I3 about its :c axis but the sta- -bilizing eilect of the gyro vertical thereon confines such angular displacement within verysmall limits.

Rlgidly supported from the underside of pendulous member I3, is a contact device denoted A generally at 3i comprising a plurality of flexible metallic leaves 32 to the ends of which are secured contacts 33 preferably made of silver. Such contacts 33 are connected along spaced taps of a resistor 35. The contact device leaves are so adjusted that about half the total number of contacts is in the normally closed position while the other half are in the normally open position (see Fig. 5) so that actuating element 31 will progressively close the contacts on one side while openingthose on the other thus simultaneously modifying the resistance in both the right and leithand portions of resistor 35. y

Assuming for the moment that actuatingl element 3l is rigidly secured with respect to support 9 then as support 9 is tilted clockwise within its I own plane the gyo assembly remaining substantially vertical will cause the left-hand portion of contact device 3| to be progressively closed while the right-hand portion will be opened. Counterclockwise rotation "or support a results in the reverse operation. At the beginning of disturbances of support sgwhen the angular displacement' 6 (see Fig. 6) is small a relatively small number of contacts are closed. The angular velocity placement angular displacement counterclockwise from normal occurs.

From the above it is obvious that means responsive to displacement only are insuincient for most purposes, since it is accompanied by sluggishness and a significant amount of huntingv which makes the system relatively unstable. A second gyroscope termed an anticipating gyro, since it anticipates corrections and is responsive tn the velocity of angular movement oi' support 9 within its own plane, that is, the velocity ofthe pitching disturbances. Such anticipating gyro performs an anti-hunting function, as will be apparent from the following description. Pivotally and perpendicularly mounted to support 9 by means oi a bearing assembly denoted generally at 38 (see also Figs. 3 and 4) is a substantially U-shaped bracket 4I within which is pivotally supported, on bearings, a block I3, in which block is clamped the motor housing 45 of the anticipating gyro, so that the center of gravity of the vanticipating gyro assembly is in the intersection of the pivot axes of the block 43. A gyro motor within the housing 45 drives the gyro wheel ti. An angle piece 49 to which is secured actuating element 31 is rigidly bolted to the outer face of the block da in such a manner that actuating element 31 is positioned between the two halves of the contact device. The sole purpose of mounting the anticipating gyro in bearing assembly 39 is to provide freedom of motion about its horizontal or torque axis so that torque forces may be transmitted to the friction damping means in a manner to be explained in more detail later in this specification. It is mentioned now to make known the fact that freedom of angular movement of the gyro about its horizontal or torque axis is limited -to such asmall degree by the friction damping means that it in no way reacts on the contact device.

With the foregoing in mind and assuming a clockwise rotation of supporting member 9 from its normal or upright position and within its own plane, it is apparent, as has hereinbefore been mentioned, that pendulous member i3, by virtue of its pendulousness and the stabilizing eifect thereon by the gyro vertical, will substantially maintain a vertical or earths center pointing position. The anticipating gyr by virtue of its mounting on support 9, shares its angular displacement. At the instant angular movement of support s begins, the anticipating gyro processes about its vertical axis in proportion to'the velocity oi' the angular displacement and so moving the actuating element 31 to close a number of the contacts on the left side while opening those on the right, thus providing for an instantaneously high restoring force, that is, force opposing disit' placement and tending to restore the gun to aimed position. As the angular displacement increases, additional contacts, are closed by the actuating element 31 due toits angular displacement with respect to the gyro vertical assembly. When the restoring force reduces the velocity of angular displacement to zero, the angular displacement is greatest and the displacement contact-closing stimulus is a maximum, while the angular velocity is zero and consequently its contact-closing stimulus is zero. 'I'he still present displacement stimulus provides for continued application of restoring force in the same sense or direction to the support 9 to move the latter ycounterclockwise with reversal of angular velocity. As the velocity stimulus is now reversed and subtracts from-therdisplacement stimulus, it opposes the return of support 9 and prevents overtravel or hunting incident to return to a condition of equilibrium. When the angular displacement reaches zero, the displacement stimulus is zero. At this point, however, the counterclockwise angular velocity is maximum, but is opposed by a high opposite force of the anticipating gyro velocity stimulus. With the displace- ,ment stimulus at zero and velocity forces opposed,

, the angular velocity of support 9 is rapidly reduced to zero in a sinusoidal manner. Fig. 6 shows graphically in a slightly exaggerated form, the displacementcurve 0 and the velocity curve g di foi support 9. From the above description and d0 the equilibrium position with the velocity action preceding the displacement action. When away from and approaching the position of equilibrium, displacement deilects contacts in the sense to eifect return to the position of equilibrium, but, as velocity reverses at the beginning of the return movement to the equilibrium position, the sense in which it acts on the contacts reverses. that is, the s-ense is in a direction to oppose return. From the foregoing. it is obvious that the anticipating gyro, by being instantly responsive to the velocity of displacement disturbances of support 9, introduces an anti-hunting eil'ect, thus providing an inherently stable yet highly sensitive control. The gyro verticals earths center pointing characteristics are utilized to provide a relative stable mounting for the contact device and to provide a means for measuring the angular displacement of support 9.

In view of the foregoing description, it is readily seen that for theV gyro stabilizer assembly to perform its function, it must be angularly displaced in the same amount as the gun'; that is. support 9 must be rotated through a corresponding number of degrees as the gun during angular movements of the tank. It must also be adjustv ably mounted with respect to the gun that it may serve to automatically position the gun in some predetermined elevation. Tank construction practically prohibits the placing of the gyro stabilizer at the trunnion axis of the gun. Previously in said copending application the stabilizing unit was pivoted to the rear of the trunnion axis on the recoil cylinder, but tanks of the type to which this invention applies have the gun mounted to permit high elevation adjustment.

With the stabilizer unit on the recoil cylinder. swinging through en are oi a radius or the units displacement from the gun trunnion axis, obstruotions were encountered during elevation movements, which restricted full adjustment of the gun. It was, therefore, impossible to mount the gyro stabilizer on the gun. A stationary pivot axis was selected and the-gyro stabilizer. connected to the gun by means of a parallelogram linkage, the description of which mounting and linkage immediately follows.

A U-shaped bracket member an inverted position to an inwardly projecting portion of the forward wall of the tank turret has mounted thereon the hand elevatingl mechanism indicated generally at b3. To the ends of the downwardly extending portions of U-bracket 5| is bolted a plate 55 which has a rearwardly extending portion 5l, to the end of which is pivotally mounted at se a member ed.

A worm wheel el is pivotally mounted on the airisV be oi member 5e and adjustebly iixed to rotate with member be by means of worm 63, which is rotatably mounted in a yoke @it piyotally mounted at et and @t on member ed insuch a position that it will engage the worm wheel 8| and be biased into engagement with said worm wheel by a spring i2 to eliminate backlash. The support s (not shown in Fig. 2 for the sake of clearness) of the gyro stabilizer assembly is bolted to the worm wheel so as to rotate with it.

The tank gun is slidably mounted in a, frame 65 which is securely bolted in a drum-like member el pivoted horizontally on trunnions 'i in an opening in the forward wall of the turret. The center of gravity of the gun assembly, except during recoil from firing, lies in the drum trunnion axis, which axis constitutes the elevation axis of the gun. Attached to the right-hand end of the drum el is a gear segment lil so positioned as `to be engaged and rotated by the worm b9 of the hand elevating mechanism et. A lbracket member 'il is mounted on the gear segment 1li by means of bolts i3 extending through the bracket and gear segment into the end of the drum 61, thus securely fastening both bracket ll and gear segment 'le to the drum bl so that they may pivot about the trunnion axis 'l.

Within the U-'shaped portion ib of bracket .5

member H is pivoted at 'il the end 'i9 of the pisasoman" Il to miter gears Il directly from the handwheel Il!! or the manual elevating mechanism 53 through shaft ii. Ro-

tation of the-handwheel |03 now directly drives tl rigidly bolted in worm B3, rotating worm wheel 6| and tilting the gyro stabilizer assembly 5 about axis 68, thusproducing an artificial pitching movement.

The worm 6o is connected with the hand-wheel |03 by spiral gears |01 and |09, and is mounted in a. housing which is pivotally mounted about the axis of handwheel shaftili so that it may be disengaged from the, gear segment during automatic elevation control of the sun. The worm 69 may be locked in either engaged or disengaged position with respect toV gear segment I0 by means of a locking device H3 so mounted in an extension lili of U-bracket E! that locking device. ||3 may engage holes in the worm housing lli when the housing is pivotally moved to either of its two positions. The dition to simplifying the connection of worm 33 to handwheel l3, also eliminates the necessity of disengaging the worm 63 from worm wheel BI when manually elevating the gun through the usualworm te and sector lll because there is freedom for the gyro unit 5 to turn. The tendi ency of the lgyro unit is to remain vertical. however. `except for differences in ratio between manual and power elevating control.

Fig. 5 shows in e. schematic way the operation E' of the entire system. A current furnished by a battery or other source of energy iii is normally equally divided between the right and left-hand portions ci' resistor 3E, since it paths extending, respectively, coils il@ and |2I. interconnected by a common valve actuating elethrough actuating ment |2'i pivoted at |29, both valves being 'normaliy open because of normal equal energize.-

ton rod 8| extending from the end of .a cylinder 83. The otherend 'of cylinder b3 is pivoted at 85 in a U-bracket di secured by bolts 8b to the 93 of the parallelogram linkage. The other end of said link 93 is pivotally secured to member 59 at 95. Pivot 95 is radially disposed with respect to axis 5t of member 5s, and pivot 92 radially disposed with respect to trunnion axis i in a manner that said pivot axes form a parallel- `pumps and valves in 4left closed path, that is,

ogram; hence, the term Parallelogram linkage.

Pitching movements of the tank will be shared,

by the gun by'means of its couple with the tank through cylinder 83 during` automatic control. The gyro stabilizer unit will be tilted an equal amount about axis 5d by the parallelogram linkage. A flexible driving shaft 91 connects Worm tion of coils'i i@ and |2| which actuate the poppet or seated-type valves |23 and |25. A motor M drivesl two simultaneously-operating pumps, for example, those provided by the motor-driven shaft iti having mounted thereon two screws |38 and i35 of reverse helix which rotate in a bore itl of pump housing |39. The output is y.

located at the extreme ends o! the shaft which is the high-pressure side of the screws, while the intake is located st the center or low-pressure side of the screws, as indicated by the arrows in the respective wits, thus forming, in effect, two separate pumps. Two separate. closed paths are indicated by the arrows between each or the and |25. Tapped on the the one normally going through valvei, is a. pipe line |4| which is connected tothe upper space in a cylinder 83.'

Similarly tapped on the right closed path, that is, the one normally going through valve |25, is a 'pipe line itt which connects to the bottom portion o the chamber of cylindere. In operation, the pendulous member I3 and the lower or anticipatins gyro, both carried by the supporting plate ,9, operate the contacts 33 to apply magnetic forces to the valves |23 and |25 to provide liquid pressures acting on the piston v|25 to oppose movement oi the gun about thetrunnion axis in response to the velocity of such movement and to return the gun to aimed position in the event of departure thereof therefrom. As the supporting plate 9 is connected to move angularly with the gun to move the gyro about'an input axis tverse to the spin axis and as the precesslon or output axis oi the angles to theforce or input axis and to the spin and IM which are driven exible drive Shaft 91, in adforms two parallel Two valves .|23 and |2i5 aregyroisarrang edatrightn axis, from the gyrodynamic relation 'T=IwW (where Lim is angular momentum of the rotor. "T" is torque about one axis of the pair transverse to the spin axis, and W is angular velocity about the other axis of the pair). it follows that angular velocity of the gun about the trunnion axis, and which velocity is applied as input to the gyro, is accompanied by proportional torque of the gyro about the output or precession axis Y-Y; and, due to the scale eiiect of the centering springs |85 and |81, hereinafter described, the angle of movement about the torque or precession axis Y--Y is a measure of the torque. Therefore, the actuator 31 is moved in proportion to angular velocity of the gun about the mounting or trunnion axis; and, as the contacts require displacement for operation, they are operated by the actuator to provide a pair of voltages whose .differential is proportional to the input velocity. As such voltages provide magnetic forces applied to the valves |23 and |25, the liquid pressures are proportional to the voltages; and, as the liquid pressures are applied to opposite faces of the piston |45, the pressure diiferential, which, from the foregoing, is proportional to angular velocity of the gun about the trunnion axis, is applied as force to the gun, opposing movement thereof. In addition to the gyro operating to minimize angular movement of the gun about the trunnion axis in response to the velocity of such movement,.the gravity responsive means, constituted by the pendulous member I3, operates the contacts to control the hydraulic motor means to maintain the support 3 in the vertical or in predetermined relation with respect to the vertical, the gun then being, in the aimed or directed position. Should the'plate 8 be deviated from this normal positional relation for any reason, then the contacts are operated to control the motor means to move the gun to restore the supporting plate to its normal positional relation. While the piston area at one side of the piston |45 is smaller than that at the other side to the extent of the cross section of the piston rod 8|, such area diierential may be compensated for, if desired, in a variety of ways, for example, lby providing for a compensating diierential of forces applied to the valves. A leakage line |41 is connected to the intake line and leads directly through the packing seal through which the piston rod reciprocates, so that as oil leakage occurs past the piston rod, the oil will be able to leak into pipe line |41 instead of forcing its way through the packing seal.

The chamber |49, which encloses the electromagnetically operated valve, constitutes a sump or reservoir. The intake of the pump, in addition to being connected to the leakage line |41, is also connected to the chamber |43.

With the worm gear G9 disengaged from gear sector l0, Fig. 2. rotation of the handwheel through flexible shaft 31 and worm 63 'drives worm Wheel El, tilting the gyro stabilizer about axis 58. Assuming for the moment handwheel rotation rotated the gyro unit clockwise, actuating element 31, as has been explained before, will progressively close the contacts 33 at the lefthand side while opening those at the right, decreasing resistance through the left-hand portion of resistor 35 while increasing the resistance through the right-hand portion. It will be seen that more current will flow through coil |2i which will effect counter-clockwise movement of valve actuating element |21 to move the valve |23 in a closing direction and further open valve |25. As a consequence of this. the pressure of the screw |86 oi' the pump will be directed into the upper chamber of the cylinder 83 to drive the piston |45 down which, by its connection at 11 with the drum 61 in which the gun is rigidly mounted, rotates said drum counterclockwise in a manner to increase the elevation of the gun. Handwheel rotation to tilt the gyro stabilizer countercloclrwise will produce an opposite eilect on the gun, decreasing the elevation angle. In e manner. pitching of the tank will tilt the gyro stabilizer in the plane of support 8 through cylinder 83 and link 93 oi the parallelogram linkage, causing an increase or decrease in the elevation oi' the gun in a manner to keep the gun trained on a distant target.

During recoil following cessively large unbalance tor-ques exist which are oi a magnitude many times greater than those ordinarily imposed upon the system. Since space limitations and the relatively short periods of recoil, usually of one-half second duration, render impractical the 'construction of a stabilizing unit suiiiciently large to cope with these large unbalances, an additional coil |50 has been added to the valve operator of valve |23 and is connected in series with the battery ||1. A recoil switch |52 of the micro-type maintained open by the gun breech is closed during recoil when the gun breech recedes therefrom, energizing the valve coil, closing valve |25, thus developing the needed pressure to support the large imbalance. A -ball or check valve |53 is installed in the pump output which leads to the bottom portion of the cylinder chamber to prevent the back pressure from entering the pump when it is in excess of the peak delivery of the pump. The hydraulic pressures in the stabilizer cylinder 33 are controlled by their respective valve currents. As the sensitivity regulator resistor |53 is adjusted to increase the change in valve currents the stabilizer accuracy is increased.

The friction damping means as used in our invention is a contribution described and claimed in a copending application of C. R. Hanna, S. J. Mikina and L. B. Lynn, Serial No. 412.612, :died September 27, 1941, entitled Electric traverse for turrets. Precessional movements of the anticipating gyro were previously damped with oil dampers described and claimed in a copending application of C. R. Hanna and L. B. Lynn, Serial No. 366.877, iled November 23, 1940, entitled Gun stabilizers, but their performance varies with changes in oil viscosity due in turn to changes in temperature. Since it is highly desirable to have a consistent gyro performance in response to differential movements, the oil damper is not always entirely satisfactory. The friction damper represents an improvement over the oil damper in both uniformity of operation and simplicity of design and adjustment. Referring to the drawings, we have in Fig. 3 a perspective showing of the anticipating gyro ofthe gyro stabilizer assembly 5. Fig. 4 is a section taken vertically through the bearing axis showing the pivotal mounting of U -bracket 4|. Centrally secured to the base of U-member 4| is a stub shaft |51. which shaft is` positioned within the inner races of ball bearings |58 and |8| axially spaced along shaft |51 at its root and extremity, respectively, by means of annular grooves |83 and |65 turned within the ends of hearing housing |81. By means of iiange |88 and a portion of the housing |61 extending through a hole in support 9, the housing is positioned and securely .bolted to firing ot the gun, ex-

by preventing axial travel the vertical axis, portional to the precessional-velocity saidsupport. A circular plate |1| of diameter slightly larger than the stub shaft |51 is fastened to the against the inner race of bellgbearlng ISE, thereof' shaft |61. A cover plate |13 is pressed into the end of the annular openinga |85. Pivotally mounted about a vertical axis in bearings in U-bracket 4| is a block 43, in the bore of which is securely clamped the motor housing 46 of the anticipating syo. The I.shaned torque transmitting arm |15 (see Fig. 3) is so positioned and secured on block t8 that its frictionally engaged end i'i'l lies between friction shoes its .and ibi adiustablv mounted on set screws in a U-bracket-i rigidly secured to support t. Itis necessary, when mounting the.

anticipating o in blocklt, that the center of gravity ot said gyro including L-shaped torque arm shalllbe in the intersection ofthe vertical or u axis and the horizontal or :c axis so that force or static unbalance may not be transmitted by the torque arm to the friction damper. Friction forces therein formed for true damping of.

precessional movements must M proportional to the velocity of angular displacement of support t within its own plane, which is a displacement velocity about the axis oi the g'yro. Any movement of the gyro about its horizontal or :c axis causes the gvro to process about its vertical or y anis against the stii restraining springs B8B and itl. Torque about the vertical axis is proportional to velocity about the horizontal axis and deflects the restraining springs itt and |81 a proportional amount. Precesslonal velocity about the vertical axis produces a reaction torque about the horizontal and the torque arm Ile and friction shoes li@ and ltd therefore engage'with a normal force proportional to this torque. But during procession about the vertical axis, the portion i'l' of arm il@ slides with respect friction developed is proportional to the applied or reaction torque, that is, torque about the s' axis due to angular displacement, which, in turn, is proportional to the precessional velocity about friction torque is developed prowhich pro duced the reaction torque. Thus, damping is proportional both to precessional velocity and reaction torque. The damping thus obtained depends upon the radius at which the friction forces act with respect to torque, upon the radius 'at which the friction forces act with respect to procession, and upon the proper coemcients offriction. The friction shoes are so adjusted to allow clearance o member |11 ofl arm |16 between their faces; .while there is slight lost motion between the shoes and the arm, itis of such a small quantity that it in no way effects the stimulus of actuating element 31. The outer ends of restraining springs |85 and |81 are stationarilyl mounted to adjustment screws E89 and |98 threaded and locked in the extremities of U-bracket |93 in turn fastened to the bottom of U-bracket 4|. Angle piece 49 at its bottom is reduced in size "and bent lnwardly. The inner ends of springs |85 and |81 are secured in holes in the'reduced portion of said angle piece. From this construction, it is obvious that the springs provide a positive return of the anticipating gyro to its normal posi tion: their stiness is also adjusted to regulate procession angles within limits as required by the control system and which stiffness at the same time prevents the gyro from responding to end of said shaft in a manner to bear choosing materials having 'aesinet vibrations or disturbances below those of a predetermined frequency, fory instance, yturning movements of the turret. Rotation of the gyro about its vertical or y axis is limitedv 'by set screws |95 and |91 threaded into the'forked end of the bottom portion of U-bracket 4|, thereby preventing excessive or damaging deilections of the contacts.- f

We are, of course,` aware-that others. particularly afterd having-,had the benefit of the teachings of lour invention. may devise other devices embodying ourv invention, and, we, therefore, do not wish to be limited -to the specific showings made inthe drawings and the descriptive disclcxsure hereirrbefore made, but Iwish to .be limited only by the scope of the appended claims.

We claim as our invention: l. In combination, a movable support provided ywith av turret, a' gun pivot -llv mounted in the turret, actuating means connecting the gun to the turret andV operative to move the gun angularly about its mounting axis, mechanism responsive to angular movement of the gunabout its mounting axis to control the actuating means for regulating the angular position of the gun with respect to such axis, and apparatus providing for mounting o said mechanism in the turret so as not tointerfere with angular movement to the friction shoes, with the result that, as the of the gun about its mounting axis; said appa- 'ratus comprising a manually-operable control element, means for transmitting angular movements from said control element to said mechanism to render the latter effective to move the 'gun angularly about its mounting axis, means for transmitting angular movements of said control element directly to the gun, and means providing for connection and disconnection of the lastnamed means. l

2. In combination, a movable support provided with. a turret, a gun pivotally mounted in :the turret, actuating means connecting the gun to the turret and operative to move the gun angularly about its mounting axis, mechanism respon--v sive to angular movement of the gun about its mounting axis to control the actuating means for regulating the angular position of the gun with respect to such axis, and apparatus providing for mounting of said mechanism in the turret so asv not to interfere |with angularv movement of the gun about its mounting axis; said apparatus comprising a bracket structure attached to the turret, an arm pivotally mounted on the bracket structure, a support for the mechanism and pivotally mounted on the bracket structure in coaxial relation with the arm, parallel-motion linkage means connecting the gun and the arm, irreversible gearing connecting the arm and the support and including a driving gear rotatablyv carried by the arm, a manually-rotatable control element carried by the bracket structure, and

means for transmitting motion from the control,V

A flexible shaft. Y

4. In combination, a movable support provided ,with a turret, a gunA pivotally mounted in the turret, a gear element connected to the gun-in coaxial relation with respect to the mounting axis, actuating means connecting the gun to the turret and operative to move the gun angularly oibout its mounting axis, mechanimn responsive to angular movement of the gun about its mounting axis to control the actuating meam for regulating the angular position of the gun about such axis, and apparatus providing for mounting of said mechanism in the turret so as not to interfere with angular movement of the gun about its mounting axis; said apparatus comprising a bracket structure attached to the turret, an arm pivotally mounted on the bracket structure, a support for the mechanism and pivotally mounted on the bracket structure in coaxial relation with the arm, parallel-motion linkage means connecting the gun and the arm, irreversible gearing connecting the arm and the support and including a driving gear rotatably carried'by the arm, a manually-operable rotary shaft carried by the bracket structure, a housing pivoted for angular movement about the axis-V of said shaft,

a driving gear rotatably carried by the housing, means including constantly meshed gears connecting the control shaft and the driving gear, means -for transmitting motion from the control shaft to the mst-mentioned driving gear, and means for positioning the housing with the second-mentioned driving gear in meshed or demeshed relation with respect to said gear element.

5. Apparatus according to claim 4 wherein the means for transmitting motion from the control shaft to the first-mentioned driving gear is comprised by a exible shaft.

CILINTONYV R. HANNA'. LAWRENCE B. LYNN. 

